Accumulated products of nano-substances such as microparticles exhibit properties that are not observed in bulk materials, and therefore much research is currently being conducted into the multidimensional ordering of microparticles with the anticipation of generating novel devices. In particular, research and development into the use of three dimensional accumulated products of microparticles as photonic crystals is thriving. Photonic crystals are substances which utilize the appearance of forbidden wavelengths, where light of specific wavelengths disappears due to refraction or diffraction or the like, within the interior of substances in which the refractive index varies periodically with a length (distance between the microparticles that form the crystal lattice) that is substantially equivalent to the wavelength of light, and have been so named because the appearance of these forbidden wavelengths is very similar to the formation of forbidden electron transition bands in semiconductor crystals.
Examples of known techniques relating to the production of accumulated products of nano-substances such as microparticles include those listed below.
(1) A method that includes incorporating a gelling agent within a microparticle solution, gelling the mixture once the microparticles have adopted a three dimensional ordered structure, and fixing the three dimensional ordered structure of microparticles within a matrix (see Patent Document 1).
(2) A method of accumulating the particles by gravity.
(3) A method that utilizes the forces of an electric field within a liquid (see Non-Patent Document 1).
(4) A method of forming an ordered structure by utilizing the repulsive forces between the surfaces of microparticles (see Patent Document 2).
(5) A method of forming a microparticle thin film, which is related to the method of ordering microparticles by utilizing the repulsive forces between the surfaces of microparticles, and includes dispersing microparticles within a medium comprising two or more liquid mixtures having different values of vapor pressure and surface tension between microparticles, and flow casting the resulting microparticle dispersion onto the surface of a substrate to form a lattice-ordered liquid film (see Patent Document 3).
(6) A method of dipping a substrate in a microparticle suspension, and then drawing the substrate out of the suspension to form a microparticle monolayer film by advection accumulation.
(7) A method of obtaining a microparticle accumulated product by inserting a microparticle solution within a comparatively narrow space between parallel surfaces, and then using a stepping motor and a linear translation device to subject the solution to oscillation at a frequency greater than the Brownian motion of the microparticles and at an amplitude approximately equal to the spacing between the two parallel surfaces (see Patent Document 4).
(8) A method that uses a self-assembled monolayer as a template for selectively ordering microparticles. In this method, by using a self-assembled monolayer (SAM) formed on a substrate as a template, and utilizing the hydrophilicity, hydrophobicity, chemical reactivity, zeta potential, molecular recognition ability or the like of the functional groups at the SAM surface, precise ordering of microparticles can be achieved (see Non-Patent Document 2).